1. Field of the Invention
The present invention relates to a contact image-sensing module, and more particularly, to a contact image-sensing module having a fingerprint-scanning function.
2. Description of the Prior Art
An individual's fingerprint is unique, and thus has gradually become one viable option with higher security protection when serving as the individual's password. Along with the popularity of electronic devices and the increase in storage volume thereof, protection of the personal information stored therein against unauthorized invasion becomes more and more important. As the result, having the individual's fingerprint serve as the password for use of electronic devices is becoming a more effective way of protecting personal information from unauthorized use.
Reference is made to FIG. 1, which shows a schematic, cross-sectional view of a prior art image-sensing module with fingerprint scanning function. The image-sensing module includes a rigid circuit substrate 71, a linear sensing element array 72, a plurality of light sources 73, a focusing device 74, and a light penetrating device 75. The linear element array 72 and light sources 73 are located on the rigid circuit substrate 71. The light penetrating device 75 is for placing a fingerprint 9 thereon. Light emitted from the light source 73 travels upwardly to the light penetrating device 75 and is reflected to the focusing device 74 by the fingerprint 9. The focusing device 74 focuses the light upon the linear sensing element array 72, which further processes the light in order to finish the fingerprint authorization task.
However, having the linear sensing element array 72 and light sources 73 on the rigid circuit substrate 71 leads to a bigger image-sensing module, contrary to current trends of increasingly minimized electronic devices. Additionally, the focusing device 74 has to be appropriately positioned somewhere so as to have the light travel to the linear sensing element array 72, leaving less room for positioning error and demanding higher assembly accuracy, both of which seriously and negatively affect the product yield.
Reference is made to FIG. 2, which is a schematic, cross-sectional view along the line 2-2 of the prior art image-sensing module shown in FIG. 1. Light sources 73 are placed under the light penetrating device 75. However, the light intensity of these light sources 73 projecting upon the light penetrating device 75 is not uniform, leading to a more complicated fingerprint image processing and thus undermining the processing efficiency. Furthermore, because of the use of a large number of light sources, the power consumption increases and shortens the lifetime of the whole image-sensing module.